FISSURELLA. 173 



F. obtusa Sowerby. PI. 38, fig. 61. 



Shell ovate, rather elevated in the middle, radiately ribbed in a 

 somewhat wrinkled manner ; ribs irregular, interstices slightly im- 

 pressed ; aperture rather small, oblong, with the sides excavated. 

 Rayed with pink and white, white rays narrow, conspicuous, pink 

 rays broader, fading into light green near the margin. The pink 

 coloring which forms the radiating bands of this species, appears 

 only in the grooves of the sculpture, and has the appearance of fine 

 lines. (Eve.) 



Cape of Good Hope. 



F. obtusa Sowb. Conch. 111. p. 7, f. 59. — Reeve, Conch. Icon., f. 

 56.— Sowb., Thes., p. 189, f. 75, 76.— Krauss, Die Sudaf. Moll. p. 

 66. 



Krauss seems to regard this as synonym of F. mutabilis. I have 

 not seen the species, and have taken both description and figure 

 from Reeve. These should be compared with the original figures 

 in the Conchological Illustrations, which show the hole of a very 

 different shape. 



F. natalensis Krauss. PI. 38, figs. 76, 77, 78. 



The shell is almost always encrusted ; eroded in the neighborhood 

 of the apex, the sides straight, rarely a little convex. The bluish- 

 black rays are unequal, being wider and more distinct on the front 

 part than upon the posterior ; and if the shell be held up toward 

 the light they may be seen faintly from the inside. Of the 45 to 50 

 riblets, 10 to 12 are somewhat stronger than the rest, and these are 

 usually situated in the white rays. All the riblets are little-raised, 

 blunt, made a little rough by the irregular growth-lines, and scarcely 

 project at the edge, which is consequently but slightly crenated. 

 The side margins are a little concave, so that the shell rests upon 

 the two ends only. The orifice is 2 - 5 lines long, 1 line wide, rounded 

 and widest at the ends, narrowed somewhat on the sides, with two little 

 teeth on each side. Interior smooth and white, the edge black and 

 white, from the color of the outside, but not really margined. The 

 muscle-impression lies about two lines from the edge. (Krauss.) 



Length 16, breadth 9"5, alt. 5 lines. 



Cape of Good Hope. 



F. natalensis Krauss, Die Siidaf. Moll., p. 66, t. 4, f. 8. — Reeve, 

 Conch. Icon. f. 15.— Sowb. Thes. Conch, iii, p. 190, f. 69. 



